Gas exchange

1. RESPIRATORY
SYSTEM
The organs that help to get oxygen
from the air into your blood, and to
get rid of carbon dioxide.

2. THE RESPIRATORY SYSTEM INCLUDES
1. Nose
2. Trachea
3. Lungs
i. Bronchi
ii. Bronchioles
iii. Alveolus
4. Intercostal muscles
5. Diaphragm

3. 1. THE NOSE
a) Air normally enters the air passages through the nose.
b) Fine hairs in the nose trap some of the dust particles in
the air.
c) The nose is moistened by mucus ( a watery liquid)
a) To make the air moist as it passes inwards
b) To traps bacteria that are carried on the air currents
d) The air is Warmed by the body temperature

4. 2. TRACHEA (WINDPIPE)
• It is made from rings of cartilage.
• Each ring is in the shape of a “C”.
• The inner lining of the windpipe has 2 types of cells
• Mucus-secreting cells
• To trap the dust particles and bacteria in the form of
mucus
• Ciliated epithelial cells
• The cilia move the mucus to the top of the windpone
where it enters the back of the mouth and it is
swallowed.

5. 3. LUNGS
3.1 THE BRONCHI AND BRONCHIOLES
• The windpipe divides into two smaller tubes, known as bronchi
(singular : bronchus).
• The bronchi divide up into many smaller tubes, called
bronchioles.
3.2 Alveolus
• After travelling into the many bronchioles, it finally passes
into some of the millions of tiny sacs called alveoli, which
have the specialised surfaces for gas exchange.

6. • An alveolus has adaptations to allow it to exchange gases
effectively.
• Large surface area
• Thin and elastic walls
• Surround by a network of blood capillaries
• Moist surface

7. 4. INTERCOSTAL MUSCLES
• The chest wall is made by the ribs and intercostal muscles.
• Each rib is attached to the backbone by a joint that allow only
a small amount of movement.
• The internal and external intercostal muscles make the ribs
move.

8. 5. THE DIAPHRAGM
• It is a large sheet of muscle attached to the edges of the tenth
pair of ribs and the backbone.
• It separates the chest cavity (lungs & heart) from the lower
body cavity.

9. Inhalation
(Process of taking air into lung)
Exhalation
(Process of expelling air from lung)

10. Inhalation Exhalation
External intercostal muscles
contract
External intercostal muscles
relax
Rib cage moves upwards and
outwards
Rib cage moves moves
downwards and inwards
The diaphragm contracts and
flattens
The diaphragm relaxes and
curves upwards
The volume of the thoracic
cavity increase
The volume of the thoracic
cavity decrease
The air pressure in the thoracic
cavity decreases
The air pressure in the thoracic
cavity inreases
Air enters the lungs Air is forced out of the lungs

11. Model to show the action of the diaphragm
i. Plastic Y tube: trachea and
bronchi
ii. Bell jar: thoracic cavity
iii. Thin rubber sheet: diaphragm
iv. Balloons: lungs
When rubber sheet is pulled
downwards, air pressure inside
bell jar is lowered. Balloons
expand
When rubber sheet is pulled
upwards, air pressure inside
bell jar increased. Balloons
contract

12. GAS EXCHANGES
• Gaseous exchange takes place in the lungs by diffusion.
• Diffusion: the movement of gas molecules from higher
concentration to lower concentration
• Oxygen diffuse from alveoli to the blood capillary
• Carbon dioxide diffuse from blood capillary to the alveoli

13. During inhalation, when fresh air is taken
into the alveoli
• There is more oxygen in this fresh air than in the blood
capillaries
• Oxygen from the alveoli diffuses into the blood capillaries
surrounding the alveoli.
• The oxygen combines with the haemoglobin the red blood
cells, producing oxyhaemoglobin
• At the same time, higher concentration of carbon dioxide in
the blood capillaries causes carbon dioxide to diffuse from
the blood capillaries into the alveoli.
• This carbon dioxide is expelled from the alveoli during
exhalation
Haemoglobin + oxygen  oxyhaemoglobin

15. [Blood circulation]
• The heart pumps the oxygenated blood out to the body cells.
• Oxygen from the oxyhaemoglobin diffuses out of the blood
capillaries into the body cell.
• Carbon dioxide in the body cells diffuses into the blood
capillaries.
• The blood capillaries now carry deoxygenated blood which is
dark/dull red in colour.
• The deoxygenated blood is finally carried back to the heart and
then to the blood capillaries surrounding the alveoli in the
lungs.
• The deoxygenated blood releases carbon dioxide to the alveoli
and absorbs oxygen, forming oxygenated blood again
Oxyhaemoglobin oxygen + haemoglobin

16. CELL RESPIRATION
• The process in which food is oxidised in the cells to get
energy
• Cell respiration takes place in all living cells, i.e. in both
plants cells and animal cells.
• Cell respiration which uses oxygen is classified as aerobic
respiration
• Some organism such as yeast and some bacteria do not use
oxygen for respiration. They carry out anaerobic respiration
Glucose + oxygen  energy + carbon dioxide +
water

17. EFFECT OF SMOKE TO
RESPIRATORY SYSTEM
• Cigarette smoke contains irritants chemical :
• A carcinogen- an agent directly involved in causing
cancer.
Nicotine cause addicted
Carbon monoxide cause death
Sulfur oxide damages lung tissues
Tar blackens the lungs and
causes them to be less
efficient for gaseous
exchange

18. DISEASES OF RESPIRATORY
SYSTEM
1. Asthma
2. Smoker’s cough
3. Bronchitis
4. Lung cancer
5. Emphysema
6. Heart disease
7. Infant death

22. ACTIVITY
1. Name the reactants of respiration
2. Name the products of respiration
3. Why do sperm require energy?
4. What is the chemical formula of glucose?
5. Why are combustion and respiration similar?
Ext: what happens to the waste products of respiration?